1. Field of the Invention
This invention relates to the field of drafting or more particularly to the field of perspective drawing. Furthermore it relates to perspective drawing machines that keep track of chosen vanishing points rather than machines that produce a perspective of an object from plane views of the object.
2. Description of the Prior Art
In the past there have been several methods to produce a perspective drawing:
A. By measuring every line to make that line point to an invisible vanishing point. PA1 B. By using educated guesses which takes many years of practice and only very experienced people produce perspective drawings in this manner. PA1 C. A special drafting table shown in FIG. 21 can be used however the vanishing points are fixed and cannot be changed and it cannot be converted to a standard drafting machine. I do not know if this machine is patented. PA1 D. There are machines that can produce a perspective drawing of an object from plane views thereof such as conventional plan, front and side elevations: one such patent is described in U.S. Pat. No. 2,714,253.
Therefore there has been a long standing need for a machine that will keep track of the chosen vanishing points and that can be alternated quickly from a left hand vanishing point to a right hand vanishing point and then to a standard drafting machine when required. There has also been a long standing need for a machine that a high school student could understand to master the technique of perspective drawing.